As far as finding someone to lose weight with, you could try a local mum's group, or something like that, maybe? You could even post a note saying that you would like to find another mum to walk with regularly? For me, it's about motivation - I need someone to make me accountable. I'm not short on ways to exercise (heck, I could even run up and down the stairs 100 times, if I wanted to find a way to exercise. ) It's getting someone to MAKE ME DO IT! You could even make an arrangement over the phone - you and friend x agree to call each other every Saturday morning and report your weight, or something like that? When you know someone is going to check on you, you'll be more likely to stick with it.
There might even be some ladies here on BB who would be able to work with you on that. A weekly weigh in, and daily encouragements/exercise reports???

About the whole diet/weight loss thing - take it on in a reasonable way. Don't commit to something you can't/won't do, or attempt a diet you'll never keep. Change your life gradually. Maybe start with drinking the water. You might find that constantly going to that pitcher on the counter, or even seeing it there reminds you not to snack. There's a big step. Then maybe, you'll see a little success on the scale, and that will make you feel great, and you'll be ready for the next step - maybe going for one 20 minute walk with the kids a couple times a week. You don't have to commit to an hour every day to see results. Then add the exercise DVD for a couple of days a week too, or something like that.
All the best!